<!DOCTYPE html>
<style type="text/css">
  #target {
    background-color: black;
    width: 100px;
    height: 100px;
  }
</style>
<script>
function onLoad() {
    var element = document.getElementById('target');
    var animation = element.animate(
        {opacity: ['0', '1']},
        {duration: Infinity, iterationStart: 4.75});
}
</script>
<body onload="onLoad()">
<div id="target"></div>
</body>
